U.S. Pat. No. 5,044,488 (Bolin) discloses a lehr loader or stacker having a vertical series of movable carriages, the lowermost of which is supported by a support structure at an elevation above the floor of the plant in which the lehr loader is installed. The lowermost carriage is moveable toward an adjacent annealing lehr to advance a linear series of glass containers on a conveyer, described in the reference as a cross-conveyer, positioned between the stacker and the lehr, transversely of the cross-conveyer into the lehr. An intermediate carriage is mounted on the lowermost carriage and is moveable with the lowermost carriage and is independently moveable with respect to the lowermost carriage in a direction parallel to the direction of movement of the cross-conveyor to keep new containers on the cross-conveyer from piling up against a pocket bar, which is carried by a pusher bar that is carried by the uppermost carriage, during the motion of the lowermost carriage toward the lehr. The third, uppermost carriage is mounted above the intermediate carriage and is moveable with the lowermost carriage and the intermediate carriage and is moveable in a vertical direction independently of the intermediate carriage and the lowermost carriage to elevate the pusher bar above the tops of the incoming containers on the cross-conveyor during the return of the pusher bar to a start position. Other lehr loaders are disclosed in U.S. Pat. No. 4,067,434 (Mumford) and U.S. Pat. No. 3,181,031 (Dunlap), which were assigned to a predecessor of the assignee of this application, the disclosure of each of which is incorporated by reference herein. An improved lehr loader of the forgoing general description is also disclosed in pending U.S. patent application Ser. No. 08/931,720, which is assigned to the assignee of this application.
Modern glass container annealing lehrs are quite wide, to be able to suitably process the output of modern, high productivity glass container forming machines. The width of the conveyer belt that carries glass containers through the lehr determines the overall required width of the pusher bar assembly of the lehr loader associated with such lehr, and a full width pocket bar for such a pusher bar assembly, of the type taught by the prior art, is subject to warpage along its length, especially in the high temperature environment in which lehr loaders are used, which often reaches, or even excedes 400.degree. F. This pusher bar warpage problem is especially severe in the case of lehr loaders designed to provide containers to annealing lehrs that have an especially large internal width.